1. Field of the Invention
The present invention relates to a process for producing L-lysine by fermentation.
2. Description of the Background
L-lysine is one of the essential amino acids. It is the first limiting amino acid of cereals and is an important amino acid used in assorted feed for broilers or swine.
In conventional processes for producing L-lysine, artificial variants of microorganisms isolated and derived from the natural world have been used. It is known that most of these artificial variants are derived from microorganisms belonging to the genus Brevibacterium or the genus Corynebacterium. It is also known that the biosynthesis system of L-lysine has been potentiated by imparting to the microorganisms properties such as auxotrophy, resistance as well as sensitivity to amino acid analogs, chemical drugs and the like in combination or adding these properties successively ("AMINO SAN HAKKO (Amino Acid Fermentation)", edited by H. Aida, K. Takinami, I. Chibata, K. Nakayama and H. Yamada; Gakkai Shuppan Center, 1986, page 273.
However, the conventional processes are quite expensive and relatively inefficient. Thus, a need exists for a process for producing L-lysine which is less expensive and which has an improved efficiency.